'Real world' hp required for 28gpm log splitter pump

[mikefromnh]

I want to build a log splitter with a 2 stage 28gpm pump.

I have a question about how much engine I really need (haven't bought anything yet)

I'm looking at using a cylinder with a max psi of 2500
Using the formula
Gpm X pressure/1714(efficency)
Or
Gpm x pressure x .0007

High flow
28x650/1714(.85) = 12.5hp

Low flow
7x2500/1714(.85) = 12.25hp

So my question -- can I go buy a "13 hp" engine and have it work?

I'm specifically thinking about the 420cc Chonda that harbor freight sells. Commercially available splitters with a 28 gpm step up to a v-twin??

 

[buickanddeere]

13HP is fine. It's going to spend a lot of time operating at low power waiting to stroke, taking up the slack to start splitting and running the return stroke. A larger motor will tend to operate too cool.

 

[J_J]

The minimum HP for that pump is 16.

This pump will also go to 3000 psi unless you adjust the relief valve on the log splitter.

If you use 12 HP engine.

12 HP, . 4 cu in, 3600 rpm, 7 GPM at 2500 psi at high pressure.

12 HP, 1.8 cu in, 3600 rpm, 28 GPM at 600 psi at low pressure.

If you use 16 HP engine 28 GPM DYNAMIC 2-STAGE PUMP

16 HP, .468 cu in, 3600 rpm, 9.5 GPM at 2500 psi.

16 HP, 1.8 cu in, 3600 rpm, 28 GPM at 850 psi.

The 22 GPM pump is matched to the 12 HP

22 GPM at 500 psi or 6.3 GPM at 3000 psi

22 GPM 2 STAGE HYD PUMP S31004-5278

13 HP = 7.5 GPM at 2500 psi.

13 HP = 28 GPM at 700 psi.

 

[mikefromnh]

Typing at same time

 

[mikefromnh]

The minimum HP for that pump is 16.

This pump will also go to 3000 psi unless you adjust the relief valve on the log splitter.

If you use 12 HP engine.

12 HP, . 4 cu in, 3600 rpm, 7 GPM at 2500 psi at high pressure.

12 HP, 1.8 cu in, 3600 rpm, 28 GPM at 600 psi at low pressure.
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16 hp at 3000 psi...But if I set the relief to 2500 and the adjusted it to go into low flow at ~600 the 13 hp should be fine with the 28gpm 2 stage pump?


I guess I'm also concerned with the claimed 13 hp of the harbor freight 420cc engine.

I don't want to build the splitter and find out the engine won't get it done.

 

[buickanddeere]

Go with JJ's advice and allow for 3000psi.
How much torque rise is there in the 13 and 16HP engines ?

 

[Scooby074]

I have a 13hp subaru on my 22gpm... Its not adequate unless I keep the pressure around 2000psi. Its one of those on paper things. I can stall it out if I crank the pressure up.

For a 28gpm, Id say you should be looking at about 18hp minimum (20+hp better) regardless of what "calculations" say. You may use a bit more fuel, but at least you'll have a bit of reserve power.

The Concentric pump chart for their 28gpm 2 stage peaks at about 20hp. Its funny, because if you look at Northern Hydraulics they say that same 28gpm pump can be ran off a 12hp motor. Thats laughable.Concentric: Diesel engine application, diesel engine oil pumps, diesel engine water pumps, diesel engine fuel transfer pumps, diesel engine components, diesel engine systems, transmission pumps, compressor pumps

 

[mikefromnh]

I have a 13hp subaru on my 22gpm... Its not adequate unless I keep the pressure around 2000psi. Its one of those on paper things. I can stall it out if I crank the pressure up.

For a 28gpm, Id say you should be looking at about 18hp minimum (20+hp better) regardless of what "calculations" say. You may use a bit more fuel, but at least you'll have a bit of reserve power.

The Concentric pump chart for their 28gpm 2 stage peaks at about 20hp. Its funny, because if you look at Northern Hydraulics they say that same 28gpm pump can be ran off a 12hp motor. Thats laughable.Concentric: Diesel engine application, diesel engine oil pumps, diesel engine water pumps, diesel engine fuel transfer pumps, diesel engine components, diesel engine systems, transmission pumps, compressor pumps

Thanks that's the feedback I was looking for. I suspect the discrepancy in the hp numbers has to do with various ways mfr's come up with their HP ratings.

Sounds like the predator 22hp vtwin might be the way to go.

 

[Scooby074]

Thanks that's the feedback I was looking for. I suspect the discrepancy in the hp numbers has to do with various ways mfr's come up with their HP ratings.

Sounds like the predator 22hp vtwin might be the way to go.

22hp is the way Id go. :thumbsup:

 

[muddstopper]

I have a 25hp engine with the 28gpm two stage pump on my splitter. Never bogs the engine and I think is really overkill. I had the engine so I used it. It is thirsty, but with the 6way wedge, it splits a lot of wood in a hurry so i live with the fuel mileage.